Question

When sugar is stirred with a spoon in a glass of water, more sugar is dissolved and faster. Why?
A. Spoon acts as a catalyst
B. On stirring, temperature increases.
C. Stirring increases the rate of interaction.
D. Spoon increases the attraction between the molecules of water and sugar.

Answer 1

Solutes dissolve in solvents in solutions in different amounts of given times is termed as rate of dissolving. A certain mass is transferred from the solid state to liquid state. It is influenced by several factors. Some of them are temperature, particle size and stirring.

Complete step by step solution: A phenomena in which a solid substance solubilizes in a given solvent is termed as dissolution. Solubility can be termed to the maximum amount of solute which can dissolve a certain mass of solvent at a fixed temperature.
Rate of dissolving is also influenced by several factors in which some of them are given below:
a)Surface area of solute
If the liquid is kept in a wider container than a smaller one, then faster is the rate of dissolving.
b)Temperature of the solution
At high temperature, faster is the rate of dissolving.
C)Particle size
When the particle size is larger, then less of the solute will be dissolved.
d)Stirring
Usually if the solution is stirred, then more is the rate of dissolving.
In the given case, sugar is stirred with a spoon, its kinetic energy is increased. So the interaction between the molecules is increased. Moreover, stirring increases the surface area, thereby the rate of dissolving increases. Since the kinetic energy is dependent on the temperature, the temperature alos decreases.

Hence the correct option is B and C.

Note: Solubility of a solute in a solvent is influenced by the following factors:
a)Nature of solute
b)Nature of solvent
c)Temperature of solution
When the temperature increases, the solubility of solids and liquids increases while the solubility of gases decreases.